NASA’s Kepler space telescope has run out of fuel and will no longer be able to continue its work as an exoplanet hunter, which it has been operating for almost a decade. NASA announced on Tuesday the end of the mission of this instrument that during the years that it has been exploring the galaxy has discovered more than 2,600 exoplanets, some of them with the necessary conditions so that, in theory, they can harbor some kind of life.
Having already exceeded the expected life expectancy, Kepler, 9 and a half years old, had been resisting time with very little fuel. Its ability to target distant stars and identify possible alien worlds visibly worsened in early October, but flight controllers managed to recover their latest observations. The telescope has now been silenced, and its fuel tank is empty.
“Kepler opened the door for humanity’s exploration of the cosmos,” said William Borucki, a retired scientist at NASA, who led Kepler’s original scientific team. The mission discovered 2,681 planets outside our solar system and even more potential candidates. It showed us rocky worlds the size of Earth that, like our planet, could harbor life. It also revealed incredible super-Earths: planets larger than ours but smaller than Neptune.
The astrophysics director of NASA, Paul Hertz, estimated that between two and a dozen planets discovered by Kepler are rocky and the size of Earth in the so-called Goldilocks zone, an area of possible habitability. However, Kepler’s general census of planets showed that 20% to 50% of the stars visible in the night sky could have planets like ours in this favorable area for life.
Kepler focused on stars thousands of light-years away and, according to NASA, showed that statistically there is at least one planet around each star in the Milky Way. In total, of about 4,000 exoplanets that have been confirmed in the last two decades, two-thirds owe it to Kepler.
“It has revolutionized our understanding of our place in the cosmos,” Hertz said, adding: “We now know from the Kepler Space Telescope and its scientific mission that planets are more common than stars in our galaxy.”
Earlier this month, the discovery of the first exoluna was announced: a satellite the size of Neptune orbiting a giant gas planet at 8,000 light years. A successor to Kepler launched in April, NASA’s Tess spacecraft has its sights on the stars closest to its home. Some possible planets have already been identified.